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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8214
Fig. 231. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
Fig. 232. Schematic and hookup of T874D with Q674G. Used in standard applications.
C1
RISE
H2
FALL
H1
FALL
H1
RISE
CO
L1
(HOT)
L2
1
2
1
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
ONLY TERMINAL B OR O TO BE USED. 0.8A MAX.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
EM. HT.
HEAT
AUTO
COOL
FAN RELAY
EM. HT. RELAY
AUX. HT. RELAY
COOL
CHANGEOVER
VALVE
HEAT CHANGEOVER
VALVE
COMPRESSOR
FAULT
H1
ANTICIPATOR
H2 ANTICIPATOR
C1
ANTICIPATOR
M5152
COMPRESSOR
RELAY
W3 RELAY
AUX. HT.
LED (GREEN)
O
L
EM. HT.
LED (RED)
G
R
E
X
W2
B
W3
Y
12
11
10
9
5
4
3
2
8
L1
(HOT)
L2
1
SYSTEM
SWITCH
OFF
H1
ANTICIPATOR
H1
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M3957
RH
C1
Y1
H2
RISE
W1
C1
ANTICIPATOR
C2
RISE
AUTO
1
4
6
8
9
10
COMPRESSOR
CONTACTOR 2
FALL
HEAT RELAY 1
RC
Y2
11
C2
ANTICIPATOR
W2
HEAT RELAY 2
COMPRESSOR
CONTACTOR 1
L1
(HOT)
L2
1
12
B
5
7
FAN RELAY
O
T
H2
ANTICIPATOR
THERMOSTAT SUBBASE SYSTEM COMPONENTS
NO FAN
SWITCH